Change-speed gearing for machine tools



Jan; 9, 1945.

A. H. LLOYD CHANG-SPEED .GEARING FOR MACHINE TOOLS Filed NOV. 20, 1942 2 4 sheets-sheet 1 Jan. 9, 1945. l A H, LQYD 2,366,974

CHANGE-SPEED GEARING FOR MACHINE TOOLS Filed Nqv. 2o, 1942 4 shets-sneet 2 Jan. 9, 1945. v A, H, LLOYD CHANGE-SPEED GEARING FOR MACHINE TooLs Filed ANOV. 20, 1942 4 Sheets-Sheet 3 Iliff/Ah.

Jan- 9, 1945. r A. H. LLOYD 2,356,974

' CHANGE-SPEED GEARINGFOR MACHINE TOOLS lFiled Nov. 2o,- 1942 4 sheets-sheet 4 ne. n. nqjnz.

Patented Jan. 9, 1945 t Arthurr I-.Iarold Lloyd, Coventry, England, as-

signor to Alfred Herbert Limited, Edgwick,

Coventry, England Application November 20, 1942, serial No. 466,340.

` In Great Britain October29, 1941 2 claims. l(o1. sol-97) This invention relates'to lathesv or other machine-tools, our mainobject being to provide an improved pre-selective change-speed gearing therefor which in some conditions `can advantageously be used instead of the preoptive gearings described 'in British patent specifications Nos. 382,784, 429,741, 434,893, 441,141, 446,772 and and another or others.

More particularly theinvention relates to a change-speed gearing ofthe kind which includes a plurality of gear pairs which can'be entrained, respectively, by slidable members (for example vfriction clutches, dog clutches orslidable gears).

A particular object of the invention is to arrange for lthe slidable ,members 'to be selectively movable by hydraulic mechanisms, on the actuation'of a master valve controlled .by a pilot valve, dependently upon the setting` of a selector valve means which carries thefluid pressure only while Y mechanisms, which are correspondingly grouped,

dependently upon the setting of a selector valve means.

`These and' other objects and ylaclvantages rkof 466,789 in the names of Alfred Herbert Limited v the invention will best be understood if attention `v be directed to the vfollowing description in which g reference is made to the accompanying sheets of diagrammatic drawings, wherein? Figure 1 is a plan of a lathe headstock accord-` ing to the invention, withv rpart of `the casing broken away to disclose the hydraulic means, the Agearing and the striking forks therefor being omitted; u Figure 2 is an end elevation of v`the headstock -with' vpart of' the casing brokeny away todisclose the striker forks andthe coacting hydraulically-l acting pinions by which they "are actuated, the hydraulic mechanisms being omitted in this case; Figure 3 is a developedview o f the gearing;

n Figure 4 is a sectional elevationalA view to a larger scalethrough the hydraulic mechanisms, the sectionu being taken mainly yon the line IV-IV of Figure 5 omitted;l i l VFigure/5 is a sectional plarrjtolthe,samev scale of the hydraulic mechanisms;

Figures 6 to 10 are fragmentarysectionalviews,

, similar'to that of Figure 4, taken on theflines but` the pilot valve being VI-VI, VII-k-VII, VIII--VIIL IX-IX and X- of Figure 5, respectively;

' Figures 11 and 12 are developed views of the rotatable sleeve and the stationary sleeve, respectively, of the selector valve means; and

Figure 13v is a developed View of anotherl form of change-speed gearing which could'be operated by the hydraulic mechanisms of Figures 4 and 12. In Figures 1 to 3, IIy represents the input shaft and I2 the spindle. On the input shaft is a sleeve I3 fast with different-sized gears I4, l5 which are respectively meshed with gears I6, I'I. A clutch I8 is provided for connecting the sleeve |3'to 'the' input shaft or for freeing it when desired.. Coacting with the gears I6, II, which are free on the shaft I9, are multi-plate clutches` 20.l Fast on the shaft-l I 9 are different-sized gears o 2|, 22 which are respectively meshed with gears 23, 24 free on a shaft 25. Associated with-thev gears 23,' 24 are multi-plate clutches which can be selectively engaged by means of a slidable co1- lar 26. Thus, by selective positioning of the slidable collars 20, 26 four different speeds can be obtained on the shaft 25.'

The latter shaft is connected in a similar way with a shaft 21 by gear pairs 28 and 29 which can be selectively entrained through multi-plate clutches by operation of a sliding collar 3|). The drive from the shaft 21 to the spindle I2 is by the gear pair 3|, and it will be observed that the gearing thus provides a choice of eight different speeds at the spindle.

In the present instance the three slidable members 20, 26, and 30 are grooved and engaged by striking forks 3 I, v32, and 33 respectively, and each lof the strikingforks is formed with 'a glut 34 (Figure 4) which is supported on a bar 35, the gluts being grouped beside one "another, as shown most clearly in Figure 2.v Each glut is formed with rack teeth 36 engaged with a pinion 3'I which is disposed beneath it. On opposite sides of each I .pinion are disposed hydraulic devices, each pair of devices comprising plungers 38, 39 working in cylinder bores, the upper ends of the plungers having secured to them rack vplates 4I engagedV with the pinion. In Figure 5 the cylinder bores associated with the striker fork 3| are marked 42, those for the striker fork 32 are marked 43, and those for the other striker fork 44.

Disposed beneath the pinions in the casing 49 of the hydraulic mechanism is the rotary element 5|I of a selector valvemeans which in the present instance is an 8-position element. The rotary element 50 is fast with a sleeve 5Ua for convenience of manufacture, and the latter sleeve turns in a sleeve 49a fast with the casing 49, the two sleeves being secured, respectively, by grub screws 53. The rotary element 50 and sleeve 50a can be turned by a spindle carrying at the front of the headstock a handwheel 52 for setting or pre-selection purposes.

The supply of the fluid pressure to the selector4 valve means is controlled by a master valve and) a pilot valve, and when the master valve is` in.

operation it provides a complete seal, thus leaving the selector valve means free of uid pressure so that the rotary element may be pre-set as desired.

` In the drawings (Figure 5) the master valve includes a casing 59 in which is a ball 60 anda plunger element 6 I. Fluid at an appropriate pres-` sure is supplied through the inlet 62, tending to unseat the ball, but the same fluid pressure passes by the passage. 6.3; through the'port `$4 and the port 65 to the underside of the. plunger element. 61|, which therefore holds. the, ball 60 in the sealing position by the pressure difference.

The pilot valve includes a waisted plunger 66 which in the position` shown in Figure 5.places the ports Gli, d5 in communication with one another. ,Itl is biassed downwardly by a spring El to the position shown, and. it carries an operatingA stem 6.8 `which `extends to the front of the headstock.

Havingv pre-set thel selector valve means-for example, to the `position shown` by Figures 4 to 10e-when the new speed is tov be introduced the operating stem Eil-.of the pilot. valve is depressed by the operator in vcharge of the. machine, and when. the lower collar 'lll on the. plunger 55. has passed the port 65,. the pressure in the space below the plunger element 5|. is placed by way of the port 85m communication with the exhaust passage l2. and the supply of pressure through the port @4 is, of course, cut off. Inthese conditions the pressure on the ball. 60. unseats the ball and the. pressure then passes by way of the passages 'I4 to rone of the ports l5. in the. rotary'sleeve 50a and to the peripheral groove 'lliv in the rotary element 50. The groove 1B communicates with longitudinalpassages Tl in the rotary element which terini-nate at the. peripheral groove 18 near the. -other end of the yrotary element. Thus, iiuid under pressure issupplied. from the groove 1.8, through the port 'i9 .in the vrotary sleeve 58a (Figures 5 and 6)., through the port 80 in the iixed sleeve 49a, `to the passage. 8|` leading to the underside of the left-hand plunger (38) of the cylinder pair 44. It. will be seen. from. Figures 5 and 8 that fluid under pressureA is also, being, supplied from the. groove S2 in the rotary element 50 through the ports 83 to, thepassage 8.4'l leading to the underside of the` left-hand plunger.(38a) of the cylinder pair 43'.. From Figures 5, and 1.0 it is apparent that the pressureisbeing supplied from the groove 85 inthe rotary element 5.0 to the ports 85 and thence by the passage 8'! to the vunderside of the right-hand plunger (39D.) of the cylinder pair 52'... Atthesame time the underside of the right-hand plunger ('39). of. the cylinder pair` M is placed in communication with the exhaust passage 38. extending along therotary element 5G' by way ofthe passage 89, the ports 90, the peripheral groove 5|, and theport SI2-see Figure 4. The underside of the.; right-hand plunger (33a) of the cylinder pair 43` `ist exhaustedI through.v the passage 93, ports 94,` and passage Sli-see Figure 7 .while the underside f thev left-hand plunger (38h). of the cylinder pair 42 exhausts through the passage 96, the ports 91, and the passage 98. Thus the striker forks 32 and 33 are moved in the same ldirection--to the right in Figure 3-and the striker fork 3| in the opposite direction.

It will be obvious that for another setting of therotary element and associated sleeve 50a the uid pressure would be applied (on the operation of the pilot valve) to the underside of the plunger 39, the underside of the plunger 38 being placed in communication with 'the exhaust, in which case the glut 34 of Figure 4 would be slid to the right. In a similar way, for any setting of the rotary` element of the selector Valve means the; other two pairs of cylinders above the bottom pair inHFigure are similarly selectively placed in communication.` with the pressure and exhaust respectively dependently upon the setting of the selector valve means. The necessary passages and ports are shown in the drawings and their arrangement will be clearto. those skilled in. the art, and' it is` not believed that furtherdescription will be necessary. y y

' Figure 11' represents. the layout ofthe ports in the rotary sleeve 50a, .and the, dottedlines represent the. grooves `andholes. in the rotary element 50; Figure 12. refers to the. stationary sleeve 49a. The ports marked/L. in Figure 12 are associated with the left-hand cylinders and thosemarkedR with the right-hand cylinders.,

The change of Speed can. take place almost instantaneously, so that it is unnecessary for the operator to ,hold thejpil'ot valveoperated, and on release of the. stemjthe` parts return to the position' shown` in Figure .5 when the diierential pressure acting upon the plunger element will again close the master valve 60, thus leaving. the selector valveA means. free to bere-set.

In the gearing of `Figure 13. the input shaft lla. can drivey the two gears |4'a, |5a, and these can be selectively meshed with the twin gears Ia, lla which are fast with a collar 20a, slidable upon the shaft Illa.. Fast on the latter are gears. Zia, 22a which can be selectively meshed' with the slidable twin gears 23a, 24av fast with a collar 26a- In a similar way the gear pairs, 28a, 29a can be selectively entrained in the drive to the shaft 21a by movement,v of the slidable collar 30a, the nal drive to the spindle |2a being by the gear pair 3|a. Obviously the three, slidable members. 20a, 26a and 30a may be engaged by striker. forks which are hydraulically actuated as described above in connection with Figures 1 to 12. In thisI case, however, the pilot valve must beheld operated until the change. has been effected, as there For cooling purposes the accumulator unit or other portions of the hydraulic system may, if desired, be disposed away from the machine-tool, for example, on the floor. adjacentthe machinetool.

By the use` of an accumulator unit only a small pump is necessary, and quickoperationof the clutches or slidablev gears, can. be. obtained. The push-button. pilot valve provides avery light control.

What I claim asmy invention and desire to secure by Letters Patent of the United States is:

1. A power unit comprising a shaft, gears on successive portions of the shaft, pairs of racks, each rack of a pair meshing with its respective shaft gear at substantially diametrically opposed points, hydraulic pistons carrying said racks, substantially vertical cylinders receiving said pistons,

a valve chamber beneath said shaft and between said cylinders ported to communicate with the lower portions of the cylinders, y and a selector valve rotatably mounted in said chamber having inlet and exhaust channels and ported to register in various angular positions with the ports of the cylinders in prearranged` sequence.

2. A power unit comprising a substantially horizontal shaft, pinions xed on said shaft, rack pairs meshing respectively with diametrically opposite portions of said pinions and arranged to reciprocate substantially vertically, hydraulic plungers carrying said racks and disposed at opposite sides of said shaft, substantially Vertical hydraulic cylinders for said plungers, a selector rotary valve disposed on a substantially horizontal axis below said shaft and between the lower portions of said cylinders and having passages com' municating with the lower portionsv of said cylin- '1 ders, means whereby said selector valve may be manually set, a source of fluid pressure supply to said selector Valve, a normally closed master valve between said source and the selector valve to normally remove pressure from the selector valve during setting, apilot valve in communication with said source and in controllable connection with said master valve, said master valve having movable parts with opposed dierential areas with the. smaller areay exposed to the pressure l ARTHUR H. LLOYD. 

